re-installing my official jellybean

hi

please how i can re-installing my official jellybean 4.1.1 on my galaxy nexus? i don't want reset factory

- because i find many problem like popup battery low. when reach to 15% always appear very annoying

-time on battery life is not correct (on the graph when you go to battery option)

-always showing charging even if i unplug the mobile

keep in mind my ROM official and i get an update from Google

i would like to reinstalling the ROM

THANK YOU